Asteroid taxonomy from cluster analysis of photometry by David J Tholen(
)3
editions published
in
1984
in
English
and held by
4 WorldCat member
libraries
worldwide
In the last few years, two major contributions to the asteroid database have been the eight-color and thermal radiometric
surveys. The former consists of broad-band photometric measurements through eight filters spanning the 0.3 to 1.1 (mu)m wavelength
range. The latter consists of thermal flux measurements at 10 and/or 20 (mu)m, and when combined with measures of the reflected
light, can yield reliable estimates of their geometric albedos

ASTEROID TAXONOMY FROM CLUSTER ANALYSIS OF PHOTOMETRY by David J Tholen(
)
in
English
and held by
0 WorldCat member
libraries
worldwide
In the last few years, two major contributions to the asteroid database have been the eight-color and thermal radiometric
surveys. The former consists of broad-band photometric measurements through eight filters spanning the 0.3 to 1.1 μm wavelength
range. The latter consists of thermal flux measurements at 10 and/or 20 μm, and when combined with measures of the reflected
light, can yield reliable estimates of their geometric albedos. Visual display of the eight-color survey data can be simplified
by reducing the dimensionality of the problem. A principal components analysis was performed to accomplish this task. The
analysis shows that 95 percent of the information contained in the seven independent color indices is contained in two principal
components. This result is due to the fact that most asteroid spectra can be explained in terms of two absorption features,
one at ultraviolet and the other at near-infrared wavelengths. The photometric and radiometric data sets were also used, along
with cluster analysis techniques, to produce an improved asteroid taxonomic system. Seven major classes are now recognized
and are designated A, C, D, E, M, P, and S. Three interesting minor classes are also identified: B, F, and G. Marginal evidence
for an eighth major class, here called T, exists in the data, but the reality of this class awaits confirmation by further
observations of potential members. Three asteroids do not fall into any of the above classes and are assigned unique designations:
R (349 Dembowska), Q (1862 Apollo), and V (4 Vesta). Four E-class asteroids are now known to exist in the main belt, yet nearly
twice this number exist in or near the Hungaria region. Twenty eight D-class asteroids have been identified in the outer belt,
where they represent a significant fraction of the population. Five D asteroids exist in the main belt, which one lying near
the inner edge of the belt, which is dominated by S-class asteroids. Two of the interesting minor classes are

Observations of Planet Crossing Asteroids(
)1
edition published
in
1999
in
English
and held by
0 WorldCat member
libraries
worldwide
This grant funds the investigation of the Solar System's planet crossing asteroid population, principally the near Earth and
trans-Neptunian objects, but also the Centaurs. Investigations include colorimetry at both visible and near infrared wavelengths,
light curve photometry, astrometry, and a pilot project to find near Earth objects with small aphelion distances, which requires
observations at small solar elongations